The present invention concerns the front bumpers of automotive vehicles and expressly relates to a device for lessening point load during vehicle impact with a pedestrian and reducing the likelihood of knee injury and pedestrian underbody entrapment.
Automotive vehicle bumper systems have long been designed primarily to absorb impact forces generated during collisions with other vehicles and/or with fixed objects. Bumper systems are typically constructed of a high strength plastic mounted to a metal bumper beam and/or frame. This bumper system typically extends across the front and rear of the vehicle and serves as an absorber and deflector upon impact.
Previous bumper designs have been effective in vehicle-to-vehicle collisions, but limitations in the design are realized during pedestrian impacts. In some vehicle collisions with upright (standing, walking, or running) pedestrians, the bumper makes contact with the pedestrian""s leg in the vicinity of the knee and there is a tendency for the pedestrian""s foot to remain planted on the ground. As the vehicle continues to move forward, the bumper forces the pedestrian""s lower leg to rotate about the foot or ankle and the bumper overrides the lower leg, resulting in potentially severe knee injury and/or the pedestrian being drawn under the vehicle.
U.S. Pat. No. 6,089,628 teaches a vertically movable stiffener for reducing or eliminating pedestrian leg injuries during a collision. The stiffener is located immediately below the bumper and extends across substantially the full width of the bumper. The stiffener is raised close to the underside of the bumper when the vehicle is operating at lower speeds so that the vehicle maintains a relatively large approach angle. When the vehicle""s speed increases, the stiffener moves downward to a height at which it will make contact with a lower part of the leg during a pedestrian impact and hinder lateral knee bending and pedestrian underbody entrapment. The movable stiffener is rigid and does not yield significantly at the point where it impacts the pedestrian""s lower leg, thus generating relatively high point loads. The deployable stiffener is also relatively complex and expensive to manufacture and install on a vehicle. Therefore, there is a need in the art to provide a bumper assembly that can be more simply and inexpensively executed, and that allows more freedom of design while reducing point load forces imparted to the pedestrian""s lower leg upon impact.
The present invention provides a bumper system for reducing injury to a pedestrian struck by an automotive vehicle by lessening the likelihood of pedestrian knee injury and underbody entrapment and reducing the point load applied to the lower leg.
These objectives are achieved by a bumper assembly comprising a bumper beam having a front surface, cushioning material such as energy absorbent high-density foam disposed on the front surface of the bumper beam, and a pedestrian protection leg spoiler secured to the bumper beam and extending downwardly and forwardly therefrom to position the leading edge of the leg spoiler below the cushioning material. The cushioning material absorbs energy of the initial impact with the leg in the vicinity of the knee, and the leg spoiler contacts the leg at a lower position. The leg spoiler has stiffness characteristics such that the impact load applied by the leg to the leading edge causes the leg spoiler to bend rearward in the manner of a cantilever beam. As it bends, the leg spoiler absorbs the impact load until reaching a maximum deflection, whereupon the leg spoiler sweeps the lower leg in the direction of vehicle travel to prevent pedestrian underbody entrapment and excessive lateral knee bending.
According to another feature of the invention, the bumper assembly further comprising an aerodynamic fascia disposed in front of the leg spoiler to improve the airflow around the bumper assembly. The fascia may also cover the front of the cushioning material and may include a grille.